Multi-layer casting process using a variety of plastic particles, plastic powder raw materials, through a number of extruders, each plastic melt plasticized, the supply of a die or distributor, the number of extruder Molten plastic synthesis after the supply die, further processing, prepared in multi-layer casting coextrusion film. Multi-layer casting coextrusion process is different from the dry process, without plastic particles made of thin film intermediate transition products, multi-layer casting co-extrusion process of economic and environmental protection. Multi-layer casting coextrusion process in the flexible packaging production enterprises widely used, reaching 80%. Multi-layer casting coextrusion process using heterogeneous plastic resin raw material co-extrusion casting, resin polar polymer compounds and resin non-polar polymer compounds between the performance difference, can learn from each other, through the resin properties of different layers, common high barrier film is prepared for high barrier film packaging. Polyethylene PE, nylon PA, TIE, EVOH resin for multi-layer co-extruded film, for dairy products, jam, meat and other vacuum packaging. Multi-layer casting coextrusion process is a number of extruders will be different functions of the resin were melt extrusion, through their respective flow in the die inside and outside the confluence, and then cast cooling composite, not only simplifies the production process, materials Less, lower raw material consumption and production costs. The use of multi-layer casting coextrusion process to produce similar structure of the casting coextrusion than other processes to save 30% of the production costs. Coextrusion Casting variety of resin materials in the molten state, in a die composite welding together, because the barrier material and heat sealing material compatibility is poor, so you must choose a good solvent. Such as co-extruded nylon-6 low-density polyethylene co-extruded film, with Bynel resin, using 11 extruders common composite die, can be extruded nylon / Bynel / LDPE11 layer composite film.At present, the typical co-extruded film structure is: tensile force layer / barrier layer / heat sealing layer / peelable layer. The main force layer is PP polypropylene, PE polyethylene, barrier layer EVOH, PA nylon, etc., heat sealing layer for HDPE, LDPE, LLDPE, CPP and so on. Resin between adjacent layers, such as poor compatibility need to add adhesive resin layer, according to the use of different materials made of different structure of the co-extruded film. Multi-layer casting co-extruded film with 11 layers of symmetrical structure and 11 layers to PA or EVOH as the barrier layer, PE for the heat sealing layer. From the functional combination, there are mainly barrier layer, heat sealing layer and adhesive resin layer, through the different combinations of polymers to meet the packaging film oxygen barrier, water vapor requirements, PA and EVOH resin raw materials for the mi...

In the processing of the film, a raw material is extruded onto another film which has been made or the different kinds of films which have been made are bonded to each other to form a multilayer film, which is called a composite film. Most of the composite film material is plastic, but can also be used paper, metal foil (usually aluminum) or fabric. The basic requirement of the composite membrane is that there is good adhesion between layers and layers to ensure the overall mechanical properties of the package. Composite film generally by the substrate, laminates, barrier materials, heat sealing materials, printing and protective coating and other components. The coextruded film has most of the characteristics of the composite film, but one difference is that all the layers of the coextruded film are extruded together at the same time, so there are no other non-plastic materials such as aluminum foil and paper. The combination of the product material is relatively small, the scope of application is also small, but because the winter layer and the layer is by hot-melt combination without adhesive, so the food packaging co-extruded film health is relatively reliable. The main characteristics of coextrusion film: good tensile properties, good surface brightness, in line with the film, a number of food film standards.

1. KBOPA Laminated Base Film In the industry standard, KBOPA oxygen transmission is required to be less than 10cm3/(m2.24h). Therefore, the actual oxygen resistance of PVDC coated nylon laminated film is about 5cm3/(m2.24h). Tip: (1) This kind of packaging can only be used below 100℃; (2) There are problems of unstable quality or coating transfer in domestic KBOPA. 2. PVA coating film Theoretically, the oxygen resistance is better than PVDC coating film, but it can only be used for 85℃ pasteurization, and the barrier is greatly affected by humidity. 3. GT film (Ceramic Evaporation Coating) It can be divided into SiOx, Al2O3 and mixed steam coating. The oxygen resistance is slightly different, but it can be less than 1cm3/(m2.24h), and it can be cooked. 4. EHA high barrier nylon film EHAP (or boiled) oxygen transmittance less than 2cm3/(m2.24h) EHAR (high temperature cooking) oxygen transmission less than 8cm3/(m2.24h) (23℃, 50%RH) 5. High barrier coating technology To apply a barrier layer through a plate roller on printing equipment. 6. High barrier adhesive It can achieve the blocking effect of PVDC co-extrusion film, and can be used for cooking purposes. 7. PVDC and EVOH co-extruded films In the GB/T28117-2011: The oxygen transmittance of PVDC co-extruded film (VDC and MA co-extruded film) and EVOH co-extruded film is less than 20cm3/(m2.24h), and the cooking resistance depends on the melting point of TiE and PO resin in the film. The type and thickness of the barrier layer resin in this kind of film directly determines the barrier property of the film, and the oxygen permeability of the good co-extrusion film can be less than 1 cm3/(m2.24h). If you want to improve the drop resistance, you need PA/PVDC, PA/EVOH co-extrusion film, at least 7 layers of co-extrusion, which can improve the tensile strength of co-extrusion film. Drop resistance depends on the toughness of the material, usually PP toughness is poor and easy to break the package, PE toughness is good but the melting point is low can not be cooked, cooking can only be HDPE, MDPE, but the transparency of the film decreased. After the multi-layer co-extruded film is compounded with a bidirectional stretch film, the tensile strength of the laminated base film increases exponentially, but the elongation decreases, and the drop resistance generally decreases, but the decrease of the laminated PA film is the least, and the decrease of the laminated PET film is more.